Early in his tenure, President Barack Obama outlined a broad nonproliferation agenda in a Prague speech. Obama told the assembled ears, and the world: "The Cold War has disappeared, but thousands of those [nuclear ] weapons have not. In a strange turn of history, the threat of global nuclear war has gone down, but the risk of a nuclear attack has gone up."

Obama moved to address his long-standing concern during a summer summit with Russian President Dmitry Medvedev in Moscow, where they agreed to conclude a pact to reduce their nuclear arsenals, perhaps by the end of the year.

A lot of voices are already expressing concern, saying such an agreement is premature -- even misguided -- and could leave the U.S. in a weaker position in an increasingly dangerous world.

In July, during a bilateral presidential summit in Moscow, the Russians and Americans agreed to work toward replacing the Cold War-era Strategic Arms Reduction Treaty, or START, which is due to expire in early December. The summit joint statement committed both countries to "achieving a nuclear-free world, while recognizing that this long-term goal will require a new emphasis on arms control and conflict resolution measures."

In a "joint understanding," both sides set targets for reducing strategic warheads and launch vehicles. This would cut each side's arsenal to a range of between 1,500 and 1,675 warheads and cut launch vehicles (e.g., submarines, missile silos and bombers) to between 500 and 1,100.

The U.S. has about 2,200 operationally deployed strategic warheads with about the same number in reserve, while Russia has about 2,800 operational warheads and an unknown number in reserve. (Some experts say the category "reserve" has little real meaning, since reserve weapons can be quickly returned to active service.)

At the moment, both sides are in the process of reducing. The 2002 Moscow Treaty requires both sides to cut nuclear deployments to between 1,700 and 2,200 operationally deployed nuclear weapons. Negotiations to make further reductions began shortly after the summit with talks in Vienna, with high hopes of finishing the new treaty before the 1991 START pact expires Dec. 5.

But experts on both sides warn it may take a few years to reach an agreement that will satisfy Washington and Moscow, especially since both parties will have to get ratification by their respective legislatures. This may be easier for Medvedev than Obama, as the Russian Duma (legislature) is led by his mentor, former president and current Prime Minister Vladimir Putin, who will have a strong say on this issue.

Obama will have to get 67 U.S. senators to sign onto the agreement. Of course, not getting the required number of votes would not prevent him from reducing the American arsenal, which he could do by presidential directive. But either way, Congress is likely to have a say about that in the end.

Despite these legislative hurdles, some critics are worried about the effect a nuclear drawdown would have on America's deterrence and international security in a world that is seeing an increasing number of nuclear weapons states.

DETERRENCE DILEMMA

Obama sees the question differently, believing that steps taken by the U.S. would give it greater moral standing in the world and, hence, more leverage in wrestling with current and future nuclear proliferation challenges. But a chorus of voices has expressed distress at major reductions in the American nuclear force structure, especially the effect it might have in a world with nearly 10 countries in the once-exclusive nuclear weapons club. Some worry whether American reductions will undermine U.S. deterrence, encouraging others such as China and North Korea to bolster their current or planned nuclear arsenals to levels closer to those of the U.S. Moreover, what effect would a drawdown have on America's Asian and European allies, which benefit from the extended deterrence of a U.S. nuclear umbrella? A weakened American posture might encourage them to obtain their own nuclear capability.

Nuclear proliferation trends are not positive. In 1998, there were six nuclear states; today there are nine, with a 10th -- Iran -- likely on the brink of having a nuclear weapons capability. Moreover, as many as 12 Arab states have declared nuclear programs to the International Atomic Energy Agency, and Venezuela signed an agreement with Russia for nuclear reactors. In addition, a nuclear program in Syria, aided by North Korea, was exposed recently and there are rampant rumors that North Korea may be helping Myanmar build a secret nuclear reactor.

Others are worried about Russia's perceived advantage in tactical, or "battlefield," nuclear weapons, which were expected to be, but in the end did not become, part of the current negotiating framework. Russia is particularly secretive about its tactical nuclear arsenal, refusing to disclose any data, even for the purposes of nonproliferation such as the Nunn-Lugar Cooperative Threat Reduction Program.

Critics argue that reducing strategic nuclear weapons to parity on both sides would give Moscow an advantage in overall nuclear capability because Russia probably has a 10:1 advantage in battlefield weapons over the U.S., according to analysts. While these nonstrategic weapons, some say numbering 13,000, would not threaten the U.S. per se, they would obviously pose a threat to U.S. forces stationed in Europe and America's NATO allies if deployed by Moscow.

More worrisome to some is that these weapons are difficult to track and easy to move, creating concerns about them falling into the wrong hands such as a terrorist's, which is rightfully a worry of the Obama administration. The anxiety does not end there: There are also worries that the expected reductions in launch vehicles, alongside strategic weapons, will undermine American conventional war-fighting capabilities.

CONVENTIONAL CUTS

According to the joint understanding, both sides have agreed to the goal of reducing strategic launch vehicles in service, such as bombers, submarines and missile silos, to a maximum of 1,100 per side. But the Russians reportedly want the new treaty to reduce launch vehicles to a maximum of 600 per side. (Moscow has 800 strategic launch systems in service, while the U.S. has 1,200.)

With only 800 delivery systems in service, some claim Moscow is pushing for the lower number to allow for the retirement of aging strategic delivery systems it no longer plans to keep in service, thereby making little, if any, hard concessions. Some have also suggested the same is true of Russia's nuclear arsenal, which is also aging, leading to charges the U.S. is making a string of unilateral concessions.

Indeed, for the Americans, reaching the 600-system level would require the U.S. to make extensive alterations to, or steep reductions in, dual-use system, such as submarines and bombers, which also have conventional warfare roles, according to experts. These observers point out that there are still plenty of conventional war scenarios on the Pentagon's shelves that would require these platforms, such as a contingency on the Korean peninsula.

In addition, some are advocating the development of a "prompt global strike" weapon, which is a conventional, rather than nuclear, warhead fitted atop a long-range ballistic missile capable of rapidly engaging a target across the globe. A weapon such as this, which could be affected by a new treaty, could strike a high-value terrorist target, a WMD-capable ballistic missile on a launch pad or even Earth-based counter-space assets, which might need kinetic attention in short order.

At this point, deployment options are being discussed. Some are advocating that such a weapon be deployed not in silos or in submarines, but above ground to make them distinguishable from U.S. nuclear forces. In either case, Moscow has asked that these new weapons be considered in the context of a new treaty, meaning that the Russians, in addition to missile defense, likely want to capture this new weapon system, too.

CONGRESSIONAL CONCERNS

This summer, Congress weighed in with its own worries about a new START, providing guidance to the White House in its negotiations with the Kremlin on any new treaty, which will ultimately require ratification by two-thirds of the Senate.

For instance, the Senate passed nonbinding resolutions in the defense bill, expressing concern about any treaty limiting U.S. space capabilities and advanced conventional weapons and required the president to report on the status of the U.S. nuclear arsenal, especially its reliability.

Because the U.S. has not tested a nuclear weapon since 1992 (although it has not ratified the Comprehensive Test Ban Treaty), some in Congress want a stockpile modernization program alongside any strategic force reductions to ensure the existing weapons are ready if needed.

Another congressional issue is missile defense. The Senate passed another resolution, indicating support for an Eastern European missile defense system and rejecting any treaty language with Russia that would limit such a deployment. As is well known, the Russians strongly oppose the so-called Third Site in Eastern Europe, slated for Poland (10 ground-based interceptors) and the Czech Republic (X-band radar), believing such a system will undermine their nuclear deterrent, even allowing for a first-strike capability. The Russians have said that moving forward on the START successor would be tied to U.S. moves on missile defense in Eastern Europe, hence the congressional concern about using it as a bargaining chip.

Capitol Hill's unease is particularly acute considering developments surrounding Iran's burgeoning nuclear and ballistic missile capabilities, which the Eastern European missile defense sites are projected to be deployed against. So far, the Obama administration has not made a decision about the Third Site, which would be an addition to existing ground-based interceptor sites in Alaska and California, but a review on the issue is expected sometime this fall.

Unfortunately, while the Russians linked nuclear arms reduction to missile defense in Eastern Europe, a few days after the summit, they publicly delinked the arms talks from helping with Iran's nuclear program, assistance the American side was seeking.

There is also some worry up on the Hill about reaching an agreement with the Russians before the Pentagon delivers its Nuclear Posture Review (NPR), which is due to the Congress in 2009 but may not be delivered until sometime in 2010. This concern is not without merit because, according to the Pentagon, the 2009 NPR "will establish U.S. nuclear deterrence policy, strategy, and force posture for the next five to 10 years and will provide a basis for the negotiation of a follow-on agreement to the Strategic Arms Reduction Treaty."

REALISTIC OR UNREAL?

Despite these challenges, some call the preliminary agreement an important, but modest, step -- one that marks progress just by the fact that its gets the parties to the table to begin negotiations on a new strategic arms reduction treaty.

Of course, there is much to be done in these talks, but the proponents expect that a new treaty will serve as a foundation for future agreements that will lead to even further drops in the number of strategic weapons. Some even see a future round of reductions addressing nondeployed -- that is, reserve -- strategic weapons as well as tactical nuclear weapons, which many experts believe needs to be dealt with soon.

While Obama called for the U.S. to lead by example -- and many see that as critical for preventing others from developing nuclear weapons -- some also caution against arms control for arms control's sake.

Others see the need for a robust nuclear arsenal in an increasingly troubling world. To these folks, a nuclear-free planet, however desirable, is not only dangerous, but in the end, little more than a pipe dream.

Former Defense Secretary, Energy Secretary and Director of Central Intelligence James Schlesinger, a man who has looked at the nuclear question from just about every angle, is one of those types. Indeed, Schlesinger recently told the Wall Street Journal that the idea of a nuclear-free world is "a combination of American utopianism and American parochialism. ... It's not based on an understanding of reality."

But one thing is for sure: The debate on this multidimensional issue is far from over, and the proceedings will not only be tracked closely in Washington and Moscow, but in places such as Beijing, Tokyo, Seoul, Taipei, Pyongyang, Brussels and Tehran.

Peter Brookes is senior fellow for National Security Affairs in the Davis Institute at The Heritage Foundation.